Stent with protruding branch portion for bifurcated vessels

ABSTRACT

The present invention is directed to a stent for use in a bifurcated body lumen having a main branch and a side branch. The stent comprises a radially expandable generally tubular stent body having proximal and distal opposing ends with a body wall having a surface extending therebetween. The surface has a geometrical configuration defining a first pattern, and the first pattern has first pattern struts and connectors arranged in a predetermined configuration. The stent also comprises a branch portion comprised of a second pattern, wherein the branch portion is at least partially detachable from the stent body.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of U.S. ProvisionalApplication No. 60/404,756, filed Aug. 21, 2002, U.S. ProvisionalApplication No. 60/487,226, filed Jul. 16, 2003, and U.S. ProvisionalApplication No. 60/488,006, filed Jul. 18, 2003, the entire contents ofwhich are incorporated herein by reference.

[0002] The present application is a continuation-in-part of co-pendingU.S. patent application Ser. No. 09/668,687, filed Sep. 22, 2000, whichis a continuation-in-part of U.S. patent application Ser. No.09/326,445, filed Jun. 4, 1999, which issued as U.S. Pat. No. 6,325,826.The present application is also a continuation-in-part of U.S. patentapplication Ser. No. 10/440,401, filed May 19, 2003 which is acontinuation of U.S. patent application Ser. No. 09/750,372, filed Dec.27, 2000, which issued as U.S. Pat. No. 6,599,316. The presentapplication is also a continuation-in-part of U.S. patent applicationSer. No. 09/963,114, filed Sep. 24, 2001, which is a continuation ofU.S. patent application Ser. No. 09/326,445. U.S. patent applicationSer. No. 09/326,445 is continuation-in-part of PCT Application No.US99/00835, filed Jan. 13, 1999, which claims the benefit of U.S. patentapplication Ser. No. 09/007,265, filed Jan. 14, 1998, which issued asU.S. Pat. No. 6,210,429, which is a continuation-in-part of U.S. patentapplication Ser. No. 08/744,002, filed Nov. 4, 1996. The entire contentsof all of the above references are incorporated herein by reference.

FIELD OF THE INVENTION

[0003] The present invention relates to the field of medical stents and,more particularly, to a stent for the treatment of lesions and otherproblems in or near a vessel bifurcation.

BACKGROUND OF THE INVENTION

[0004] A stent is an endoprosthesis scaffold or other device thattypically is intraluminally placed or implanted within a vein, artery,or other tubular body organ for treating an occlusion, stenosis,aneurysm, collapse, dissection, or weakened, diseased, or abnormallydilated vessel or vessel wall, by expanding the vessel or by reinforcingthe vessel wall. In particular, stents are quite commonly implanted intothe coronary, cardiac, pulmonary, neurovascular, peripheral vascular,renal, gastrointenstinal and reproductive systems, and have beensuccessfully implanted in the urinary tract, the bile duct, theesophagus, the tracheo-bronchial tree and the brain, to reinforce thesebody organs. Two important current widespread applications for stentsare for improving angioplasty results by preventing elastic recoil andremodeling of the vessel wall and for treating dissections in bloodvessel walls caused by balloon angioplasty of coronary arteries, as wellas peripheral arteries, by pressing together the intimal flaps in thelumen at the site of the dissection. Conventional stents have been usedfor treating more complex vascular problems, such as lesions at or nearbifurcation points in the vascular system, where a secondary arterybranches out of a larger, main artery, with limited success rates.

[0005] Conventional stent technology is relatively well developed.Conventional stent designs typically feature a straight tubular, singletype cellular structure, configuration, or pattern that is repetitivethrough translation along the longitudinal axis. In many stent designs,the repeating structure, configuration, or pattern has strut andconnecting members that impede blood flow at bifurcations. Furthermore,the configuration of struts and connecting members may obstruct the useof post-operative devices to treat a branch vessel in the region of avessel bifurcation. For example, deployment of a first stent in the mainlumen may prevent a physician from inserting a branch stent through theostium of a branch vessel of a vessel bifurcation in cases wheretreatment of the main vessel is suboptimal because of displaced diseasedtissue (for example, due to plaque shifting or “snow plowing”),occlusion, vessel spasm, dissection with or without intimal flaps,thrombosis, embolism, and/or other vascular diseases. As a result, thephysician may choose either to insert a stent into the branch in casesin which such additional treatment may otherwise be unnecessary, oralternatively the physician may elect not to treat, or to “sacrifice”,such side lumen. Accordingly, the use of regular stents to treatdiseased vessels at or near a vessel bifurcation may create a risk ofcompromising the benefit of stent usage to the patient after the initialprocedure and in future procedures on the main vessel, branch vessels,and/or the bifurcation point.

[0006] A regular stent is designed in view of conflicting considerationsof coverage versus access. For example, to promote coverage, the cellstructure size of the stent may be minimized for optimally supporting avessel wall, thereby preventing or reducing tissue prolapse. To promoteaccess, the cell size may be maximized for providing accessibility ofblood flow and of a potentially future implanted branch stent to branchvessels, thereby preventing “stent jailing”, and minimizing the amountof implanted material. Regular stent design has typically compromisedone consideration for the other in an attempt to address both. Problemsthe present inventors observed involving side branch jailing, fear ofplaque shifting, total occlusion, and difficulty of the procedure arecontinuing to drive the present inventors' into the development ofnovel, non-conventional or special stents, which are easier, safer, andmore reliable to use for treating the above-indicated variety ofvascular disorders.

[0007] Although conventional stents are routinely used in clinicalprocedures, clinical data shows that these stents are not capable ofcompletely preventing in-stent restenosis (ISR) or restenosis caused byintimal hyperplasia. In-stent restenosis is the reoccurrence of thenarrowing or blockage of an artery in the area covered by the stentfollowing stent implantation. Patients treated with coronary stents cansuffer from in- stent restenosis.

[0008] Many pharmacological attempts have been made to reduce the amountof restenosis caused by intimal hyperplasia. Many of these attempts havedealt with the systemic delivery of drugs via oral or intravascularintroduction. However, success with the systemic approach has beenlimited.

[0009] Systemic delivery of drugs is inherently limited since it isdifficult to achieve constant drug delivery to the inflicted region andsince systemically administered drugs often cycle through concentrationpeaks and valleys, resulting in time periods of toxicity andineffectiveness. Therefore, to be effective, anti-restenosis drugsshould be delivered in a localized manner.

[0010] One approach for localized drug delivery utilizes stents asdelivery vehicles. For example, stents seeded with transfectedendothelial cells expressing bacterial beta-galactosidase or humantissue-type plasminogen activator were utilized as therapeutic proteindelivery vehicles. See, e.g., Dichek, D. A. et al., “Seeding ofIntravascular Stents With Genetically Engineered Endothelial Cells”,Circulation, 80: 1347-1353 (1989).

[0011] U.S. Pat. No. 5,679,400, International Patent Application WO91/12779, entitled “Intraluminal Drug Eluting Prosthesis,” andInternational Patent Application WO 90/13332, entitled “Stent WithSustained Drug Delivery” disclose stent devices capable of deliveringantiplatelet agents, anticoagulant agents, antimigratory agents,antimetabolic agents, and other anti-restenosis drugs.

[0012] U.S. Pat. Nos. 6,273,913, 6,383,215, 6,258,121, 6,231,600,5,837,008, 5,824,048, 5,679,400 and 5,609,629 teach stents coated withvarious pharmaceutical agents such as Rapamycin, 17-beta-estradiol,Taxol and Dexamethasone.

[0013] Although prior art references disclose numerous stentsconfigurations coated with one or more distinct anti-restenosis agents,they do not disclose the inventive stent design of the presentapplication. There is, therefore, a need for a stent design that caneffectively provide ostial branch support in a vessel bifurcation andeffectively act as a delivery vehicle for drugs useful in preventingrestenosis. This is particularly true in complicated cases, such aslesions located at a bifurcation.

SUMMARY OF THE INVENTION

[0014] The present invention is directed to a stent for use in abifurcated body lumen having a main branch and a side branch. The stentcomprises a radially expandable generally tubular stent body havingproximal and distal opposing ends with a body wall having a surfaceextending therebetween. The surface has a geometrical configurationdefining a first pattern, and the first pattern has first pattern strutsand connectors arranged in a predetermined configuration. The stent alsocomprises a branch portion comprised of a second pattern, wherein thebranch portion is at least partially detachable from the stent body.

[0015] In one embodiment, the second pattern is configured according tothe first pattern having at least one absent connector, and in anotherembodiment, the second pattern has a plurality of absent connectors. Thesecond pattern may have second pattern struts, and the second patternstruts can be more densely packed than the first pattern struts.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedto provide what is believed to be the most useful and readily understooddescription of the principles and conceptual aspects of the invention.In this regard, no attempt is made to show structural details of theinvention in more detail than is necessary for a fundamentalunderstanding of the invention, the description taken with the drawingsmaking apparent to those skilled in the art how the invention may beembodied in practice.

[0017] In the drawings:

[0018]FIG. 1 is an illustration of a blood vessel bifurcation having anobstruction;

[0019] FIGS. 2-4 are illustrations of prior art stents implemented at ablood vessel bifurcation;

[0020]FIG. 5 is a flat view of an embodiment of an unexpanded stent inaccordance with the present invention;

[0021]FIG. 6 is an enlarged view of a portion of the unexpanded stentshown in FIG. 5;

[0022]FIG. 7 is a perspective view of the expandable branch portion ofthe stent of FIG. 5 in the expanded configuration;

[0023]FIG. 8 is an enlarged view of a portion of another embodiment of astent according to the present invention;

[0024]FIG. 9 is an enlarged view of a portion of an alternativeembodiment of a stent according to the present invention;

[0025]FIG. 10 is a perspective view of the expandable branch portion ofthe stent of FIG. 9 in the expanded configuration;

[0026]FIG. 11 is a schematic view of the stent of FIG. 5 in the expandedstate implemented at a blood vessel bifurcation;

[0027]FIG. 12 is a schematic view of the stent of FIG. 9 in the expandedstate implemented at a blood vessel bifurcation;

[0028]FIG. 13 is an enlarged view of a portion of another embodiment ofa stent according to the present invention;

[0029]FIG. 14 is a flat view of another embodiment of an unexpandedstent in accordance with the present invention;

[0030]FIG. 15 is an enlarged view of a portion of the unexpanded stentshown in FIG. 14;

[0031]FIG. 16 is a view of a portion of another embodiment of a stentaccording to the present invention;

[0032]FIG. 17 is a flat view of another embodiment of an unexpandedstent in accordance with the present invention;

[0033]FIG. 18 is a perspective view of the expandable branch portion ofthe stent of FIG. 17 in the expanded configuration;

[0034]FIG. 19 is a flat view of another embodiment of an unexpandedstent in accordance with the present invention;

[0035]FIG. 20 is an enlarged view of a portion of the stent of FIG. 19;

[0036]FIG. 21 is a view of the expandable branch portion of the stent ofFIG. 19 in the expanded configuration;

[0037]FIG. 22 is a flat view of another embodiment of an unexpandedstent in accordance with the present invention;

[0038]FIG. 23 is a flat view of another embodiment of an unexpandedstent in accordance with the present invention;

[0039]FIG. 24 is a view of an expandable branch portion of the stent ofFIG. 23 in the expanded condition;

[0040] FIGS. 25-28 are illustrations of the steps for a method ofinserting a stent of the present invention, according to one embodiment.

[0041] FIGS. 29-31 are illustrations of the steps for another method ofinserting a stent of the present invention.

[0042]FIG. 32 is a view of a herniated balloon for use with the methodof FIGS. 29-31; and

[0043]FIG. 33 is a view of another stent delivery system for inserting astent in accordance with another method of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] The present invention relates to stents for placement at vesselbifurcations and are generally configured to at least partially cover aportion of a branch vessel as well as a main vessel. Referring to FIG.1, an exemplary blood vessel bifurcation 1 is shown, having a mainvessel 2 extending along a main vessel axis 3 and a branch vessel 4extending along a branch vessel axis 5. Main vessel 2 and branch vessel4 are disposed at an angle 11 of less than 90 degrees. An obstruction 6is located within bifurcation 1, spanning or at least partiallyobstructing main vessel 2 and a proximal portion branch vessel 4.

[0045] Prior attempts at relieving main vessel 2 and branch vessel 4from obstruction 6, such as the one depicted in FIG. 1, have beenproblematic. Referring to FIGS. 2-4, examples of prior methods andstructures for stenting an obstructed bifurcation are shown. As shown inFIG. 2, a first stent 8 is introduced into main vessel 2 and an accesshole or side opening in the wall of stent 8 is usually created with aballoon to provide access to branch vessel 4 and unobstructed blood flowthereto. Typically, the access hole is created by deforming the strutsand connectors of the main stent pattern, which may also deform the areaof the stent surrounding the created opening and lead to undesirableresults. Also, if stent 8 is used alone, at least a portion ofobstruction 6 located within branch vessel 4 is left without stentcoverage. Referring to FIGS. 3 and 4, one prior solution has been tointroduce a second stent 10 into branch vessel 4, for example via asecond catheter inserted through a side opening of first stent 8. As canbe seen in FIGS. 3 and 4, such a configuration may introduce additionalproblems. For example, as shown in FIG. 3, second stent 10 may notprovide full coverage of the portion of obstruction 6 in branch vessel 4due to the angle 11 of the side branch vessel 4 with respect to mainvessel 2 and the fact that the ends of the stent typically define aright angle to the longitudinal axis of the lumen. Alternatively, secondstent 10 may extend beyond the bifurcation into main vessel 2, as shownin FIG. 4, and cause potential obstruction of blood flow in main vessel2 and/or cause problems at the overlapping portions of stents 8 and 10.

[0046] Referring now to FIGS. 5-7, a stent 12 according to oneembodiment of the present invention comprises stent body or wall 14extending along a longitudinal axis 16 from a proximal end 20 to adistal end 22 and defining a lumen 18 therein. Stent 12 may have athree-dimensional geometrical configuration having variable dimensions(length, width, height, depth, thickness, etc.). In a preferredembodiment, stent body 14 is a generally tubular structure. As definedherein, “tubular” can include an elongate structure that has variedcross-sections and does not require that the cross-section be circular.For example, the cross-section of stent wall 14 may be generally oval.In an alternate embodiment, stent body 14 is generally cylindrical.Also, the stent body 14 may have varied cross-sectional shapes along thelongitudinal axis 16 of the stent. For example, the circumferences inthe proximal and distal parts of the stent may be different. This mayoccur, for example, if during stent delivery the delivery system causesthe stent to distend. Lumen 18 represents the inner volumetric spacebounded by stent body 14. In a preferred embodiment, stent 12 isradially expandable from an unexpanded state to an expanded state toallow the stent to expand radially and support the main vessel. In theunexpanded state, stent body 14 defines a lumen 18 having a firstvolume, and in the expanded state, stent body 14 defines a lumen 18having a second volume larger than the first volume.

[0047]FIG. 5 shows stent 12 in an unexpanded state in a flattenedelevational view. As shown in FIG. 5, stent body 14 has a generallycellular configuration and comprises a generally repeatable series ofstruts 24 and connectors 26 configured in a predetermined general,overall, or main pattern along the length of stent 12. Struts 24comprise a pair of longitudinal strut portions 25 joined by a curvedportion 27 at the proximal ends. Struts 24 are interconnected by curvedportion 29 at the distal ends and formed into rings 28 that extend aboutthe circumference of stent 12. A series of the circumferential rings 28are spaced apart from one another longitudinally along the entire lengthof stent 12, and connectors 26 connect rings 28 to each otherlongitudinally. Connectors 26 extend generally longitudinally betweenadjacent circumferential rings 28 and connect to the respective curvedportions 25, 29 of longitudinally adjacent struts 24 of adjacent rings28. In a preferred embodiment, connectors 26 are generally S-shaped orzigzag-shaped, although other patterns may also be used. Details ofpatterns that may be used for stent 12 are described more fully inco-pending PCT application IL02/00840, filed Oct. 20, 2002, incorporatedherein by reference in its entirety. Furthermore, many other strut andconnector patterns may be used, and the present pattern is shown forillustration purposes only.

[0048] Stent 12 further includes a branch portion 30 located at somepoint along the length of stent 12. Branch portion 30 comprises asection or portion of stent wall 14 that is configured to extend into abranch vessel in a vessel bifurcation. In general, branch portion 30 isconfigured to be movable from an unextended position to an extendedposition. In the unextended position, branch portion 30 is disposed inthe volume defined by the unexpanded stent 12, that is, the branchportion 30 does not protrude radially from stent wall 14. In theextended position, the branch portion 30 extends outwardly from stentwall 14 and branch portion 30 is extended into the branch vessel. Asbest seen in FIG. 6, branch portion 30 comprises a stent wall section ofstent body 14 that is initially flush, coplanar, or cocylindrical withthe remainder of stent body 14 and may extend outwardly with respect tothe remainder of stent body 14. In this regard, branch portion 30 isgenerally adjacent an opening, slit, space, void, or other incongruityin the overall or main pattern of stent body 14. This configurationallows for access into a branch vessel, and at the same time allows forcircumferential alignment of the stent within the vessel prior todeployment. In other embodiments, multiple branch portions can beincorporated into the stent to permit multiple access to one or morevessels. In a preferred embodiment, branch portion 30 may be positionedin the midsection of stent 12. In alternate embodiments, branch portion30 may be positioned anywhere along the length of stent 12.

[0049] As best seen in FIG. 6, in a first embodiment, branch portion 30comprises a portion of branch ring 32 and is positioned adjacent andproximal to an opening 34. Upon extension of branch portion 30, theportion of branch ring 32 adjacent opening 34 extends into the branchvessel, whereas the circumferential ring 28 adjacent branch ring 32 doesnot extend into the branch vessel. Opening 34 is formed by an absence ofat least one connector 26 adjoining branch ring 32 with a branchopposing ring 33. In some embodiments, four adjacent connectors areabsent; however, in alternate embodiments any number of connectors maybe absent to create opening 34. In this embodiment, branch ring 32 issubstantially similar geometrically to circumferential rings 28 andcomprises branch ring struts 36 substantially similar to struts 24;however, a plurality of adjacent struts are free from connectors 26adjacent opening 34. In this regard, branch ring 32 is at leastpartially detachable from stent body 14 to facilitate at least a portionof branch ring 32 to extend outwardly with respect to stent body 14. Insome embodiments, the geometry of branch ring 32 may vary with respectto circumferential rings 28, and branch ring struts 36 may havedifferent configurations than struts 24.

[0050] When stent 12 is expanded, as shown in FIG. 7, branch portion 30is extended into the branch vessel, causing a portion of branch ring 32to at least partially cover the inner surface of the branch vessel 4.Thus, in a preferred embodiment, the stent coverage in the branch vesselincludes at least partial coverage of the proximal side of the innerbranch vessel wall.

[0051] Various alternative embodiments provide varying geometries ofbranch portion 30. For example, branch ring 32 may vary with respect tocircumferential rings 28, and branch ring struts 36 may have differentconfigurations than struts 24. In one alternate embodiment, branch ringstruts 36 are longer than struts 24. In another embodiment, branch ringstruts 36 are more closely packed circumferentially, resulting in agreater number of branch ring struts 36 per area within branch ring 32as compared to circumferential rings 28. In another embodiment, branchring struts 36 may be thinner than struts 24. In yet another embodiment,branch ring struts 36 may be made of a different material than struts24.

[0052] Referring to FIG. 8, another alternate embodiment of stent 19 isshown wherein a branch portion 30 comprises a branch ring 32 havingbranch ring struts 36 that are longer than struts 24 and a greaternumber of branch ring struts 36 provided as compared to the number ofstruts 24 in circumferential rings 28, resulting in a more closelypacked branch ring 32. Furthermore, the number of branch ring connectors38 on both sides of branch ring 32 is lower per branch strut 36 than thenumber of connectors 26 per strut 24. Opening 34 is adjacent branch ring32 on a distal side thereof, and the distal ends 46 of at least one, andpreferably a plurality, of branch ring struts 40, 42, 44 are free fromconnectors and detachable from stent body 14. In this embodiment, twobranch ring struts 48 and 50 positioned laterally adjacent struts 40,42, and 44 have proximal ends 52 free from connectors. In this regard,free proximal ends 52 provide less resistance to movement of branch ring32 during outward expansion with respect to stent body 14. This sameprocedure can be used to provide one, two, three or more proximal endsin the ring free of connectors. Additionally, the shape andconfiguration of branch ring connectors 38 is different than those ofconnectors 26. For example branch ring connectors along the proximalside of branch ring 32 are longer than connectors 26 to facilitategreater expansion of branch portion 30 into a vessel side branch. Also,branch ring connectors along the distal side of branch ring 32 areshaped and oriented differently than connectors 26 to facilitate greaterexpansion of branch portion 30 into the branch vessel. In alternateembodiments, branch ring connectors 38 may also differ among themselves.Also, the longer branch ring struts 36 are generally more flexible thancomparable shorter struts because the added length permits moredeflection. Also, the added length permits greater coverage vessel wallcoverage due to deeper penetration into the branch vessel duringextension. In alternate embodiments, different geometries andorientations of branch ring connectors 38 may be used.

[0053] Referring to FIG. 9, another alternate embodiment of stent 29 isshown having a branch portion 30 similar to that of the embodiment ofFIG. 8, except branch ring struts 40, 42, and 44 are longer than theother branch ring struts 36, and the distal ends thereof define anarcuate profile to the proximal side of opening 34. Also, central strut42 is longer than struts 40, 44 adjacent to strut 42. In this regard,when branch portion 30 is extended, struts 40, 42, and 44 extend furtherinto the branch vessel and provide more coverage of the vessel wall thanthe embodiment depicted in FIG. 8. In this regard, this embodiment maymore readily cover an obstruction in a bifurcation vessel such as theone depicted in FIG. 1 and, therefore, may provide better blood flow toa branch vessel. Furthermore, as described in more detail below, thisembodiment facilitates the use of a second stent in the branch vessel.

[0054] Referring to FIG. 10, stent 29 of FIG. 9 is shown in an expandedstate with branch portion 30 extended into the branch vessel, causingbranch ring 32 to at least partially cover the inner surface of thebranch vessel on the proximal side. The distal end of strut 42 of branchring 32 extends further into the branch vessel than the distal ends ofstruts 40, 44 because strut 42 is longer in this embodiment thanadjacent struts 40, 44. In this regard, a generally tapered, straight orlinear profile along the distal perimeter of branch portion 30 iscreated when branch portion 30 is expanded into the branch vessel.

[0055] Referring to FIGS. 11 and 12, schematic views are shown of stents12, 29 of FIGS. 5 and 9, respectively, in the expanded state asimplemented at a blood vessel bifurcation. As shown in FIG. 11, stent 19of the embodiment of FIG. 8 has a generally curved or radial profilealong the distal perimeter 45 of branch portion 30 as it extends intobranch vessel 4. The generally curved or radial profile is due to theparticular geometry of branch portion 30 of stent 19 of the embodimentof FIG. 8. In particular, because all of the branch ring struts 36 ofbranch ring 32 are of equal length in this embodiment, the distal endsof struts 36 radially expand equidistantly into branch vessel 4, therebycreating a generally curved or radial profile along the distal perimeter45 of branch portion 30. Referring to FIG. 12, stent 29 of theembodiment of FIG. 9 has a generally tapered, straight or linear profilealong the distal perimeter 47 of the branch portion 30 of the stent asit extends into branch vessel 4. The generally straight or linearprofile in FIG. 12 is a result of the particular geometry of branchportion 30 of stent 29 of the embodiment of FIG. 9. In particular,because central strut 42 of branch ring 32 is longer in this embodimentthan struts 40, 44 adjacent to strut 42, the distal end of strut 42extends further into branch vessel 4 than the distal ends of struts 40,44, as best seen in FIG. 10, thus creating a generally tapered, straightor linear profile along the distal perimeter of branch portion 30. In apreferred embodiment, the linear profile is at a right angle withrespect to the axis of branch vessel 4. In alternative embodiments,however, the linear profile may be at any angle with respect to the axisof branch vessel 4. One advantageous feature of the linear profile alongthe distal perimeter of branch portion 30 shown in FIG. 12 is that if asecond stent 51 were to be used in branch vessel 4, the linear profilefacilitates better alignment with the second stent and permits coverageof a larger surface area of the branch vessel wall. For example, if asecond stent 51 were to be used in combination with stent 12 of FIG. 11,gaps may exist between the two stents at the interface between theradial distal perimeter 45 and an abutting straight or linear edge of asecond stent, whereas a close abutting interface may be achieved withstent 29 of FIG. 12.

[0056] Referring to FIG. 13, another embodiment of stent 39 is shownhaving an alternative embodiment of a branch portion 30 similar to thatof the embodiment of FIG. 9, except lateral branch ring struts 48 and 50are longer than the other branch ring struts 36, and the proximal ends52 of branch ring struts 48, 50 extend proximally beyond the otherbranch ring struts into a space between the branch ring 32 and theadjacent circumferential ring 28. Branch ring struts 48, 50 haveproximal ends 52 free from connectors and provide less resistance tomovement of branch ring 32 during outward expansion with respect tostent body 14. In this regard, the longer lateral branch ring struts 48,50 function similar to a hinge and further facilitate extension ofbranch ring portion 30 outwardly, which may accommodate a branch vesseldisposed at a greater angle 11 (FIG. 1) as compared to stent 29 of theembodiment of FIG. 9. Again, since struts 40, 42, and 44 are longer thanbranch ring struts 36, they are more flexible and provide more coverageof a vessel wall than the embodiment depicted in FIG. 8.

[0057] Referring now to FIGS. 14 and 15, another embodiment of stent 49is shown having a stent body 14 that has a longitudinal section 53 thathas a different pattern than main pattern 54. Longitudinal section 53comprises a generally repeatable series of struts 56 and connectors 58that are smaller in dimension than struts 24 and connectors 26, but areformed into a similar geometrical pattern as main pattern 54. In thisregard, the struts 56 are more numerous per area within rings 28, andrings 28 are more numerous per area in section 53 because the length ofstruts 56 is shorter than the length of struts 24 and the length ofconnectors 58 is shorter than the length of connectors 26. In apreferred embodiment, the same number of connectors 58 extend betweenadjacent rings 28; however, because the struts are more numerous inlongitudinal section 53, connectors 58 extend longitudinally betweenevery other strut of adjacent rings 28. As shown in FIG. 15, stent 49further includes a branch portion 30 positioned within section 53.Branch portion 30 comprises a branch ring 32 adjacent an opening 34.Opening 34 is formed by an absence of at least one connector 26adjoining branch ring 32 with branch opposing ring 33. In a preferredembodiment, two adjacent connectors are absent; however, in alternateembodiments any number of connectors may be absent to create opening 34.In this embodiment, branch ring 32 is substantially similargeometrically to circumferential rings 28 and comprises branch ringstruts 36 substantially similar to struts 56; however, a plurality ofadjacent struts are free from a connectors 58 adjacent opening 34 andbranch ring 32 is at least partially detachable from stent body 14 atopening 34 to facilitate at least a portion of branch ring 32 to extendoutwardly with respect to stent body 14. The generally smaller strutsand connectors of longitudinal section 53 provide for freer movement ofthe strut and connector material and facilitate conformance to a vesselwall. The smaller struts and connectors also provide for a relativelymore dense surface area coverage of the branch vessel wall, which may beadvantageous in achieving a more uniform coverage around the ostium. Inparticular, this embodiment may provide particularly advantageouscoverage of a geometrically complex obstruction in a bifurcation vesselsince the relatively small pattern may flex or contour around theobstruction and provide coverage therefor. Also, this embodiment isadvantageous for relatively small obstructions as the smaller patternmay cover more surface area of obstruction.

[0058] Referring to FIG. 16, another embodiment of stent 59 is shown andincludes an alternate branch portion 30 comprising a portion of threeadjacent branch ring sections 60, 62, 64 connected and extendingcircumferentially from two adjacent circumferential rings 28. Branchring sections 60, 62, 64 each includes a plurality of branch struts 66and are connected in the longitudinal direction by branch connectors 68.Struts 66 are shorter longitudinally than struts 24 of rings 28 andconnectors 68 are smaller than connectors 26. The distal ring 60 isadjacent opening 34 and the distal ends of struts 66 of ring 60 aredetachable from stent body 14 at opening 34 to permit extension of atleast a portion of branch ring sections 60, 62, 64 to expand outwardlywith respect to stent body 14. In this embodiment, the three branch ringsections 60, 62, 64 may extend outwardly in a more radial fashion andthis branch portion 30 may be particularly advantageous for adapting orconforming to the shape of the proximal side of the ostium. Furthermore,the branch portion of this embodiment may more readily extend or flexaround an obstruction in a bifurcation vessel such as the one depictedin FIG. 1 while providing branch wall coverage and better blood flow tothe branch vessel.

[0059] Referring to FIGS. 17 and 18, an alternate embodiment of stent 69is shown and includes an alternate branch portion 30. In this particularembodiment, branch portion 30 comprises support struts 70 and anexpandable ring 72. Branch portion 30 defines at least one side opening74. In one embodiment, the dimensions of the cell defining side opening74 are such that the side opening 74 (prior to expansion of the stent)is larger than other openings in stent body 14. The presence of sideopening 74 is generally configured to accommodate a side sheaththerethrough and allow a physician to access a branch vessel during orafter a procedure. In a particular embodiment, as shown in FIG. 17, sideopening 74 is surrounded by expandable ring 72 of continuous material.In alternative embodiments, expandable ring 72 comprises unattachedportions, or one portion that only partially covers side opening 74. Aseries of support struts 70 connect expandable ring 72 with struts 24and connectors 26. Support struts 70 preferably comprise patterns in afolded or wrap-around configuration that at least partially straightenout during expansion, allowing expandable ring 72 to protrude into thebranch vessel.

[0060] In this embodiment, when stent 69 is expanded, as shown in FIG.18, branch portion 30 is extended into the branch vessel, causingexpandable ring 74 to at least partially cover the inner surface of thebranch vessel. Thus, in a preferred embodiment, the stent coverage in aportion the branch vessel includes the full circumference of the innerbranch vessel wall. In alternative embodiments, partial coverage orseveral sections of coverage are present.

[0061] Referring to FIGS. 19-21, another embodiment of a stent 79 isshown having a main stent body 14 and another embodiment of a branchportion 30. FIGS. 19 and 20 show stent 79 in the unexpanded conditionwhere branch portion 30 has not been deployed. FIG. 21 shows the stent79 in the expanded configuration where the branch portion 30 has beenexpanded. As shown, main stent body 14 includes a main stent patternhaving a generally repeatable ring 28 and connector 26 pattern. Branchportion 30 and the surrounding midsection 80 interrupt the repeatablering 28 and connector 26 pattern of stent 79. In this embodiment, branchportion 30 is configured to be both radially expandable andlongitudinally extendable into the branch vessel and relative to itslongitudinal axis 83 so that, in a preferred embodiment, the branchportion 30 contacts the entire periphery or circumference of the innerwall of the branch vessel in the expanded configuration. In this regard,branch portion 30 preferably provides 360° coverage of the wall of thebranch vessel. That is, branch portion 30 can be extended outward withrespect to longitudinal axis 81 of stent 79, and can also be expandedradially about axis 83 so as to contact the vessel (thereby allowing itto be adjustable with respect to vessel size).

[0062] Referring to FIG. 20, an enlarged view of section 80 of stent 79is shown. In a preferred embodiment, a structural support member 84 maybe provided as a transition between the main stent body 14 and branchportion 30. In one aspect of a preferred embodiment, structural supportmember 84 may be elliptical to accommodate branch vessels extending atan angle to the main vessel. In alternate embodiment, other shapes ofsupport member 84 can be used to accommodate the vasculature. Thestructural support member 84 may include a continuous ring. In thisembodiment, structural support member 84 is a full, non-expandable ringand it does not expand radially beyond a particular circumference.

[0063] As shown in FIGS. 19 and 20, two concentric rings, inner ring 86and outer ring 88, are positioned within structural support member 84and surround a generally circular central branch opening 34 to provideaccess to the side branch vessel when stent 79 is in the unexpandedcondition. Rings 86 and 88 are interconnected by a plurality of innerconnectors 90. Outer ring 88 is connected to structural support member84 by a plurality of outer connectors 92. Rings 86 and 88 are generallycurvilinear members. For example, rings 86, 88 can be defined byundulation petals, prongs, or peaks 94. In a preferred embodiment, eachring 86, 88 have the same number of undulation peaks 94, but the innerring may be more closely or tightly arranged, as shown. In anotherpreferred embodiment, each ring 86, 88 has eight pedals or undulationpeaks 94, although in alternate embodiments each ring can have anynumber of undulation peaks, and the number of peaks need not be equalfor each ring. The undulation peaks 94 generally include a pair of strutportions 96 interconnected by curved portions 98, and the strut portionsthemselves are connected to adjacent strut portions by another curvedportion. In a preferred embodiment, eight outer connectors 92 extendbetween structural support member 84 and outer ring 88, and each outerconnector 92 is attached at one end to approximately the middle of astrut portion 96 of outer ring 88 and the structural support member 84at the other end. As shown, outer connectors 92 may also have anundulated shape, although in alternate embodiments outer connectors 92may have differing shapes. In another aspect of the preferredembodiment, outer connectors 92 may be evenly or symmetrically spacedabout the structural support member 84. The inner ring 86 is attached tothe outer ring 88 by a plurality of inner connectors 90 and, in apreferred embodiment, eight inner connectors 90 connect the rings. Innerconnectors 90 extend from curved portion 98 of outer ring 88 to curvedportion of inner ring 86. As shown in FIG. 20, in a preferredembodiment, inner connectors 90 have a simple curved shape. Otherquantities, configurations, sizes and arrangements of connectors, ringsand spacing can be used depending upon the desired results. Varying theconnectors can provide for different amounts of flexibility andcoverage. The type of configuration of rings and connectors shownaddresses the need for radial and longitudinal expansion of branchportion 30, as well as branch vessel coverage. Other configurations andarrangements for the branch portion can be used in accordance with theinvention.

[0064] Referring again to FIGS. 19 and 20, the stent pattern surroundingbranch portion 30 may be modified with a different pattern toaccommodate branch portion 30, as can all of the aforementionedembodiments. In particular, the rings 28 in the midsection 80 may beconfigured and dimensioned to be denser to provide sufficient coverageand flexibility to compensate for the area occupied by branch portion30.

[0065] Referring now to FIG. 21, stent 79 is shown in the expandedconfiguration, with branch portion 30 deployed. Upon expansion of branchportion 30, the inner and outer rings 86, 88 shift about thelongitudinal branch axis 83 and expand laterally away from the mainstent body 14 and into the branch vessel to form a branch coverageportion. Upon expansion, the outer connectors 92 can move outwardly andthe inner connectors 90 can straighten to a position substantiallyparallel to longitudinal branch axis 83. In a preferred embodiment, theexpanded rings 86, 88 have substantially the same expanded diameter,although in alternate embodiments rings 86, 88 could also have differentdiameters to accommodate a tapered vessel, if, for example a taperedballoon is used. The branch portion 30 can be extended at differentangles to the longitudinal axis 81 of the stent depending upon thegeometry of the branch vessel being treated. In this embodiment, thebranch portion 30 may preferably extend into the branch vessel about1.5-3 mm.

[0066] Referring now to FIG. 22, another embodiment of a stent 89 isshown having a main stent body 14 and another embodiment of a branchportion 30. Stent 89 is substantially similar to stent 79, except stent89 has a discontinuous support member 104 surrounding a two concentricring 86, 88 structure. Support member 104 has a generally ellipticalshape and includes a plurality of discontinuities 106 along theperimeter. The configuration of the discontinuous support memberfacilitates additional flexibility of the branch portion duringexpansion and generally provides for accommodating a greater range ofbranch vessel geometries. In one aspect of a preferred embodiment,structural support member 84 may be elliptical to accommodate branchvessels extending at an angle to the main vessel.

[0067] Referring to FIGS. 23 and 24, another embodiment of a stent 99 isshown in the unexpanded and expanded states, respectively. Stent 99comprises a main stent body 14 and another embodiment of a branchportion 30. Stent 99 is substantially similar to stent 79, except stent99 has a branch portion 30 including a support member 108 surroundingthree concentric rings 110, 112, 114 instead of two. As can be seen inFIG. 24, when stent 99 is expanded the three concentric ring structureof this embodiment facilitates additional branch wall support because agenerally more dense pattern is created in branch portion 30 with theaddition of another concentric ring.

[0068] In all of the above embodiments, the branch portion 30 protrudesinto the branch vessel when the stent is fully expanded. The branchportion upon expansion can extend into the branch vessel in differentlengths depending upon the application. The amount of extension may varyin a range between about 0.1-10.0 mm. In one preferred embodiment, thelength of extension is 1-3 mm. In another preferred embodiment, thelength of extension is approximately 2 mm. In alternative embodiments,the amount of extension into the branch vessel may be variable fordifferent circumferential segments of branch portion 30. As shown ineach of the embodiments, the branch portion is approximately 2.5 mm inwidth and about 2.5 -3.0 mm in length. However, the branch portion canbe dimensioned to accommodate varying size branch vessels. The branchportion can be formed of any tubular shape to accommodate the branchvessel, including, oval or circular, for example.

[0069] In general, a wide variety of delivery systems and deploymentmethods may be used with the aforementioned stent embodiments. Forexample, a catheter system may be used for insertion and the stent maybe balloon expandable or self-expandable, or the stent may be balloonexpandable and the branch portion self-expandable, or vice versa. Oncethe stent is in position in the main vessel and the branch portion isaligned with the side branch the stent can be expanded. If the stent isballoon expandable, the stent may be expanded with a single expansion ormultiple expansions. In particular, the stent can be deployed on a stentdelivery system having a balloon catheter and side sheath as described,for example, in U.S. Pat. Nos. 6,325,826 and 6,210,429, the entirecontents of which are incorporated herein by reference. In one preferredembodiment, a kissing balloon technique may be used, whereby one balloonis configured to expand the stent and the other balloon is configured toextend branch portion 30. After the main portion of the stent isexpanded in the main vessel, the stent delivery system may be removedand a second balloon may be passed through the side hole in the branchportion and expanded to expand the branch portion of the stent. In analternate embodiment, the same balloon may be inserted in the mainvessel inflated, deflated, retracted and inserted into the branchvessel, and then reinflated to expand branch portion 30 and cause it toprotrude into the branch vessel. Alternatively, the stent can bedelivered on two balloons and the main portion and the branch portioncan be expanded simultaneously. As needed, the branch portion can befurther expanded with another balloon or balloons. Yet anotheralternative is to use a specially shaped balloon that is capable ofexpanding the main and branch portions simultaneously. The stent canalso be deployed with other types of stent delivery systems.Alternatively, the stent, or portions of the stent, can be made of aself-expanding material, and expansion may be accomplished by usingself-expanding materials for the stent or at least branch portion 30thereof, such as Nitinol, Cobalt Chromium, or by using other memoryalloys as are well known in the prior art.

[0070] The construction and operation of catheters suitable for thepurpose of the present invention are further described in U.S. patentapplication Ser. No. 09/663,111, filed Sep. 15, 2000, which is acontinuation-in-part of U.S. patent application Ser. No. 09/614,472,filed Jul. 11, 2000, which is a continuation-in-part of U.S. patentapplication Ser. Nos. 09/325,996, filed Jun. 4, 1999, and 09/455,299,filed Dec. 6, 1999, the disclosures of all of which are incorporatedherein by reference. It should be noted that the catheters taught in theabove applications are exemplary, and that other catheters that aresuitable with the stents of the subject application are included withinthe scope of the present application. In alternative embodiments,catheters without balloons may be used. For example, if the stent iscomprised of memory alloy such as Nitinol or Cobalt Chromium, or is amechanically self-expanding stent, balloons are not necessarily includedon the catheters. Furthermore, any other catheter, including ones thatare not disclosed herein, may be used to position stents according tothe present invention.

[0071] Referring now to FIGS. 25-28, illustrations of the steps of oneexample of a method for employing a stent according to the invention areshown. By way of example, the method is depicted utilizing stent 12.Methods for positioning such a catheter system within a vessel andpositioning such a system at or near a bifurcation are described morefully in co-pending U.S. patent application Ser. No. 10/320,719 filed onDec. 17, 2002, which is incorporated herein by reference in itsentirety. As shown in FIG. 25, a catheter system 120 is positionedproximal to a bifurcation, using any known method. A branch guidewire122 is then advanced through an opening in the stent and into the branchvessel 4, as shown in FIG. 26. In a preferred embodiment, the openingmay be a designated side branch opening, such as an opening formed bythe absence of some connectors 26, as described above. Branch portion 30is adjacent the opening. As shown in FIG. 27, if the side sheath 124 isattached to the main catheter 120, the main catheter 120 is advancedalong with the side catheter 124. Alternatively, if the side sheath 124is separate from to the main catheter 120, the second catheter or sidesheath 124 is then advanced independently through the opening in thestent and into the branch vessel. Branch portion 30 is positioned over aportion of the lumen of the branch vessel 4 as the side sheath 124 isinserted into branch vessel 4. Referring to FIG. 28, a first balloon 126located on main catheter 120 is then expanded, causing expansion of thestent body, and a second balloon 128 located on the second catheter orside sheath 124 is also expanded, causing branch portion 30 to be pushedoutward with respect to the stent body, thus providing stent coverage ofat least a portion of the branch vessel. The balloons are then deflatedand the catheter system and guidewires are then removed.

[0072] Referring now to FIGS. 29-31, illustrations of the steps ofanother method for employing a stent of the present invention is shown.By way of example, the method is depicted utilizing stent 12. Thedepicted method may be accomplished using a catheter system having amain catheter 131 including a herniated balloon 135 (FIG. 32). Inparticular, the stent can be deployed on a stent delivery system havinga herniated balloon as described, for example, in U.S. patentapplication Ser. No. 60/488,006, filed Jul. 18, 2003, the entirecontents of which are incorporated herein by reference. As shown in FIG.29, the catheter 131 includes a balloon 135 that has a protrudingportion 137 that protrudes outwardly from the cylindrical outer surface134 of the balloon.

[0073] Referring to FIG. 32, the herniated balloon 135, shown in anexpanded state, has a generally cylindrical shape and the protrudingportion 137 can be any appendage or integral portion of the balloon thatmoves outwardly from the outer surface 134 of the balloon uponinflation, in accordance with the principles of the invention. In apreferred embodiment, the protruding portion 137 is a portion of theballoon wall that has greater expandability than other portions of theballoon wall that retain a generally cylindrical shape. In anotherembodiment, protruding portion 137 may be a solid structure attached tothe balloon wall. The protruding portion 137 can have any shapedesirable to effect deployment of branch portion 30. In one preferredembodiment, protruding portion 137 has a hemispherical shape. In anotherpreferred embodiment, protruding portion 137 has an ovoid shape. In use,the stent 12 is crimped onto the balloon 135 so that the protrudingportion 137 is positioned at the branch portion. As shown, theprotruding portion 137 is positioned adjacent or alongside the radiallyinward side of branch portion 30. The herniated balloon 135 is used toexpand the branch portion 30 and/or deploy the outwardly deployablestructure of stent 12 by applying a force in the laterally outwarddirection to the expandable elements by deflecting these elements towardthe side branch 4. The protruding portion 137 may be located at anyposition along the length of the balloon. For example, it can be locatedon the middle ⅓ of the stent.

[0074] In one embodiment, the balloon may be constructed of compositematerials. For example, a combination of elastomeric and semi to noncompliant materials such as urethane, silicone, and latex, (Elastomeric)polyethylene hytrel pebax polyarylethertherketone, polyoxymethylene,polyamide, polyester thermoplastic polyetheretherketone andpolypropylene (semi to non compliant), may be used. The balloon may alsobe constructed by combining the above-mentioned materials with woventextiles such as Kevlar, silk cotton, wool, etc. In this construction, atextile is wound or woven onto a rod that has the shape of the desiredherniated balloon and the polymer is then extruded or dip coated overthe rod. The composite is cured, heat set or adhesively fused together.The rod is then removed and the remaining shape is a herniated balloon.The balloon can also be constructed by adding an appendage to aconventional balloon by using a molded collar or adhesively attaching anobject to the surface of the balloon or by using a mound of adhesive tocreate the herniation or protruding portion. In an alternate embodiment,the balloon can be constructed by molding three small balloons andattaching them in tandem with the center balloon being round in shape.The balloon would share a common inflation port. When the balloon isinflated the center balloon becomes the herniation.

[0075] Referring again to FIGS. 29-31, protruding portion 137 may beconfigured to fit directly into an opening in the stent. As shown inFIG. 29, catheter 131 is advanced over a guidewire 133 and positionedproximal to the bifurcation. As shown in FIG. 30, the catheter isadvanced until the protruding portion 137 of the balloon is positionedat the bifurcation. In one embodiment, protruding portion 137 protrudesoutwardly from catheter 131 enough so that it actually comes intocontact with the bifurcation, thus providing a method of alignment withthe branch vessel 4. Finally, as shown in FIG. 31, balloon 135 isexpanded, which simultaneously causes the stent to expand and branchportion 30 to be pushed toward the branch vessel 4. Upon inflation ofthe balloon, the herniated portion 137 expands and extends through thebranch portion 30 toward the side branch to open the entrance of theoccluded side branch artery.

[0076] In an alternative method, the stent can be delivered using aherniated balloon and a dual lumen delivery system. This system caninclude a main catheter defining a first lumen with concentric guidewirelumen and balloon inflation lumen, a herniated balloon, as describedabove, on the main catheter, a side sheath with a guidewire lumen, and astent. The stent is crimped over the main catheter, balloon and sidesheath with the side sheath exiting the stent through a branch openingor side hole. The distal end of the side sheath is used for aligning thestent branch opening with the branch vessel 4.

[0077] In another embodiment, the appendage or herniation may be locatedon a second catheter or side sheath of the delivery system, such as thesystem 138 depicted in FIG. 33. In this case, the system is atwo-balloon system. The smaller balloon 140 can be positioned in thestent in a similar manner as the herniation. The appendage or herniationmay have an inflation lumen 141 and a lumen for receiving a guidewire142 for locating the branch vessel 4.

[0078] One particular application for the use of a stent with a branchportion 30 such as the one described above is for localized drugdelivery. As was discussed hereinabove, restenosis, including in-stentrestenosis, is a common problem associated with medical proceduresinvolving the vasculature. Pharmaceutical agents have been found to behelpful in treating and/or preventing restenosis, and these are bestdelivered locally to the site of potential or actual restenosis, ratherthan systemically.

[0079] As used herein, the term “preventing” includes stopping orreducing the occurrence or severity of a disease or condition or thesymptoms of the disease or condition.

[0080] As used herein, the term “treating” includes substantiallyreducing the severity of a disease or condition or the symptoms of thedisease or condition, or substantially reducing the appearance of adisease or condition or the symptoms of the disease or condition. Theterm “treating” includes substantially completely abolishing a diseaseor condition or the symptoms of the disease or condition. The term“treating” also encompasses preventing, stopping, or reducing theoccurrence or severity of a disease or condition or the symptoms of thedisease or condition.

[0081] When—as with anti-restenosis drugs, for example—a drug is usefulprimarily at a particular body site, systemic administration is notnecessary and is often undesirable. For instance, systemicadministration of drugs often results in undesirable side effects. Also,it is difficult to achieve constant drug delivery to a site needingtreatment using systemic delivery methods. Drugs administeredsystemically often cycle through concentration peaks and valleys,resulting in time periods of toxicity and ineffectiveness. In contrast,drugs delivered in a localized manner can be delivered at a highconcentration at the site(s) where treatment is needed, while minimizingthe systemic concentration of the drug, thus minimizing or eliminatingside effects. Additionally, localized delivery facilitates themaintenance of appropriate drug levels at the treatment site, withminimal undesired fluctuation.

[0082] Stents according to the present invention may have one or moredrug depots on and/or in the stent wall. As used herein, the term“depot” describes a store of at least one drug designed to retain andthereafter release the drug(s). According to current technology,materials incorporating drug(s) are often associated with stents bycoating the drug-containing material(s) onto the walls of the stents.Thus, “coating” is referred to and used herein in describing thedepot(s), but this use is solely for convenience of explanation and isin no way limiting, and other methods of associating drug(s) with stentsthat are currently available or that may become available arespecifically contemplated. As another non-limiting example, as isdiscussed further hereinbelow, stents may be “seeded” with geneticallyengineered cells that secrete or otherwise release drug(s). As yetanother non-limiting example, biocompatible polymers incorporatingdrug(s) may be molded into a solid mass of a desired size and shape andattached to the stent using pharmaceutically acceptable methods.

[0083] The term “depot” refers generally to an area of a stent that iscoated or otherwise associated with drug(s) or a material incorporatingdrug(s). Any given depot is generally discrete from other depots. Forexample, in certain embodiments, a depot may consist of a discrete massof material incorporating drug(s). As another example, because the wallsof stents according to the present invention comprise open spaces, adepot may also include spaces. A depot may include open spaces, forexample, in embodiments where drug(s) or a material incorporatingdrug(s) is coated or seeded onto a stent to form the depot. One depotmay abut, or be adjacent to a second depot, but the second depot willgenerally have different drug(s) and/or different concentration(s) ofdrug(s), as is discussed in further depth hereinbelow.

[0084] It will be understood that depot(s) of stents according to thepresent invention can be “on” or “in” the stent walls. For example,where it is desired to release drugs(s) primarily to the cells of thevessel walls at the site of placement of a stent, it may be desirable tocoat, attach a drug-containing mass, or otherwise associate drug(s) withonly the outer side of the stent wall. As another example, when it isdesired to deliver drug(s) to an organ, tissue, or region of the bodydownstream from a stent, it may be desirable to coat, attach adrug-containing mass, or otherwise associate drug(s) with only the innerside of the stent wall. In still other embodiments, it may be desirableto coat, attach a drug-containing mass, or otherwise associate drug(s)with the inner side of the stent wall, the outer side of the stent wall,and/or the portions of the stent wall that face inward to the openspaces within the wall.

[0085] The terms “drug,” “drug compound,” and “pharmaceutical agents”are used interchangeably herein, unless stated otherwise. These termsare meant to be construed broadly, to mean pharmaceutically acceptablesubstances (i.e., substances that are safe for use in the body of amammal such as a human) and that have some biological effect on cells ofthe body. The terms also include substances that are being tested forsafety for use in the body of a mammal such as a human and/or todetermine whether (or what) biological effect they have on cells of thebody. Examples of types of molecules that may be drugs as the term isdefined herein include, but are not limited to, proteins and peptides,small molecules, antibodies, multi-cyclical molecules, macrolides, andnucleic acids. The general and specific examples provided herein, aswell as similar substances, are included in the term “drugs” accordingto the present invention.

[0086] Depots of stents according to the present invention are capablereleasing, or eluting, the stored drug(s). Hence, the depots of thepresent invention can be made of any material that can entrap,encapsulate, adhere, or otherwise retain and thereafter release thestored drug(s). Depots of stents according to the present invention arepreferably capable of controllably releasing drug(s). Hence, the depotsof the present invention are preferably made of any material that canentrap, encapsulate, adhere or otherwise retain and controllably releasethe stored drug(s).

[0087] The phrases “controllably release”, “controllable release,” and“controllably releasing” are used herein to describe a release ofdrug(s) at a predetermined rate and duration under selected conditions.Slow release is one form of controllable release.

[0088] In certain preferable embodiments, depots of the presentinvention comprise one or more biocompatible polymer(s) loaded withdrug(s). In certain embodiments, the biocompatible polymer utilizedminimizes irritation to the wall of the lumen where the stent isimplanted. Methods for incorporating biocompatible polymers loaded withdrug(s) into or onto stents generally involve coating the stent with thepolymer(s) and are well known in the art. See, e.g., U.S. Pat. No.5,679,400.

[0089] Several configurations for loading drug(s) into biocompatiblepolymers are envisaged by the present invention. The drug(s) may be, forexample, molded into the polymer, entrapped or encapsulated within thepolymer, covalently attached to the polymer, physically adhered to thepolymer, or otherwise incorporated into the biocompatible polymer.

[0090] The biocompatible polymer may be, for example, either a biostablepolymer or a biodegradable polymer, depending on factors such as thedesired rate of release or the desired degree of polymer stability underphysiological conditions.

[0091] Biodegradable polymers that are usable in the context of thepresent invention include, without limitation, poly(L-lactic add),polycaprolactone, poly(lactide-co-glycolide), poly(hydroxybutyrate),poly(hydroxybutyrate-co-valerate), polydioxanone, polyorthoester,polyanhydride, poly(glycolic acid), poly(D,L-lactic acid), poly(glycolicacid-co-trimethylene carbonate), polyphosphoester, polyphosphoesterurethane, poly(amino acids), cyanoacrylates, poly(trimethylenecarbonate), poly(iminocarbonate), copoly(ether-esters) (e.g. PEO/PLA),polyalkylene oxalates, polyphosphazenes and biomolecules such as fibrin,fibrinogen, cellulose, starch, collagen and hyaluronic acid.

[0092] Biostable polymers that are usable in the context of the presentinvention include, without limitation, polyurethanes, silicones,polyesters, polyolefins, polyisobutylene, ethylene-alphaolefincopolymers; acrylic polymers and copolymers, vinyl halide polymers andcopolymers, such as polyvinyl chloride; polyvinyl ethers, such aspolyvinyl methyl ether; polyvinylidene halides, such as polyvinylidenefluoride and polyvinylidene chloride; polyacrylonitrile, polyvinylketones; polyvinyl aromatics, such as polystyrene, polyvinyl esters,such as polyvinyl acetate; copolymers of vinyl monomers with each otherand olefins, such as ethylene-methyl methacrylate copolymers,acrylonitrile-styrene copolymers, ABS resins, and ethylene-vinyl acetatecopolymers; polyamides, such as Nylon 66 and polycaprolactam; alkydresins; polycarbonates; polyoxymethylenes; polyimides; polyethers; epoxyresins; polyurethanes; rayon; rayon-triacetate; cellulose, celluloseacetate, cellulose butyrate; cellulose acetate butyrate; cellophane;cellulose nitrate; cellulose propionate; cellulose ethers; andcarboxymethyl cellulose.

[0093] In certain other embodiments, depot(s) on or in stents accordingto the present invention comprise liposomes into which drug(s) have beenencapsulated or entrapped. Methods for incorporating liposomes loadedwith drug(s) into or onto stents generally involve coating the stentwith the polymer(s) and are known in the art. See, e.g., Kallinteri P.et al. “Dexamethasone incorporating liposomes: an in vitro study oftheir applicability as a slow releasing delivery system of dexamethasonefrom covered metallic stents,” Biomaterials 23(24): 4819-26 (2002). Inyet other embodiments, depot(s) depot(s) on or in stents according tothe present invention comprise genetically engineered cells that secreteor otherwise release desired drug(s), e.g., therapeutic protein(s).Methods for incorporating genetically engineered cells into or ontostents generally involve seeding the cells onto the stent and are knownin the art. See, e.g., Dichek, D. A. et al., “Seeding of IntravascularStents With Genetically Engineered Endothelial Cells”, Circulation, 80:1347-1353 (1989); Flugelman M. Y. et al., “Genetically engineeredendothelial cells remain adherent and viable after stent deployment andexposure to flow in vitro,” Circ Res., 70: 348-54 (1992).

[0094] One or more depots may be present at any location in or on thewalls of stents according to the present invention. Depot(s) may beutilized with any and all stents according to the present invention.Depot(s) may be present in or on the wall of the main vessel portion ofstents according to the present invention. Similarly, depot(s) may bepresent in or on the wall of the branch portion of stents according tothe present invention. The position of depot(s) depends on desiredsite(s) of highest concentration of drug delivery.

[0095] The size of depot(s) on or in stents of the present inventiondepends on various parameters, such as the material of which the stentbody is fabricated, the permeability of the stent body and the depot,the efficacy of the depot in retaining the drug(s), the concentration ofthe drug(s), and the desired rate and duration of release of thedrug(s). Depot(s) may extend around the entire, or only a portion of,the circumference of main vessel portions of stents according to thepresent invention. Likewise, depot(s) may extend longitudinally for allor only a portion of the length of main vessel portions of stentsaccording to the present invention. With regard to branch portions ofstents according to the present invention, depot(s) may cover all oronly a portion of the walls, or may be in all or only a portion of thewalls.

[0096] When it is desired to increase the overall volume of a depot, itmay often be preferable to increase the length and/or width of thedepot, rather than its thickness, or depth. In other words, it may oftenbe preferable to increase the size of a depot along or within the wallof a stent, rather than extending the depot farther into the lumen ofthe stent. Depot(s) that extend too far into the lumen of a stent mayimpede fluid flow through the stent, and depots that are too thick onthe outside wall may deform the stent into the vessel, also impedingfluid flow. However, it may be desirable to concentrate a large volumeof depot in a small surface area, to maximize drug concentration to asmall section of vessel. Contrariwise, it may in other instances bedesirable to have drug(s) released along a large section of vessel, inwhich cases it may be desirable to use a depot that has a large surfacearea along or within a wall of the stent.

[0097] Thus, the length, width, and thickness of a depot are variablesthat can be tailored according to the desired drug distribution and thesize of the main and branch vessels to be treated. For example, a depotthat is thick enough to impede fluid flow in a narrow vessel may be anoptimal thickness for a larger vessel.

[0098] Additionally, the concentration of drug(s) in a depot can bevaried according to the desired rate of elution of the drug from thedepot and the desired concentration of the drug in the local area of thedepot. Thus, the parameters of depot length, width, and thickness anddrug concentration can be varied to tailor depots to elute the desiredconcentration of drug(s) to the desired area(s) in vessels of varyingsizes.

[0099] Non-limiting examples of anti-restenosis drugs that may beincorporated into depot(s) in or on stents according to the presentinvention include anticoagulant agents, antiproliferative agents,antimigratory agents, antimetabolic agents, anti-inflammatory agents,and immunosuppressive substances, and combinations thereof. Particularlyuseful anti-restenosis drugs include paclitaxel, rapamycin, and HDACinhibitors. Examples of histone deacetylase (HDAC) inhibitors, which areefficient inhibitors of smooth muscle cell (SMC) proliferation, include,without limitation, hydroxamic acids such as trichostatin A (TSA),suberoyl anilide hydroxamic acid (SAHA), oxamflatin, m-carboxycinnamicacid bishydroxamide (CBHA), cyclic hydroxamic acid-containing peptide 1(CHAP1), cyclic hydroxamic acid-containing peptide 31 (CHAP31), subericbishydroxamate (SBHA), pyroxamide, and scriptaid. Further detailspertaining to an HDAC inhibitors, their use, and stents incorporatingsame are disclosed in a U.S. Provisional Patent Application assigned toa common assignee of the present invention, filed Jul. 24, 2002,Attorney Docket No. 03/23768, entitled “STENTS CAPABLE OF CONTROLLABLYRELEASING HISTONE DEACETYLASE INHIBITORS,” incorporated by referenceherein in its entirety.

[0100] In addition to anti-restenosis drugs, stents according to thepresent invention can also be used as vehicles for localized delivery ofother drugs. As a non-limiting example, stents of the present inventionare particularly useful in for localized delivery of anti-thromboticdrugs. Thrombosis (the formation of a thrombus, or blot clot) sometimesoccurs in association with medical procedures involving the vasculature.For example, thrombosis may result from physical injury of an arterialwall by a vascular interventional procedure such as percutaneoustransluminal coronary angioplasty (“PTCA”; a type of balloonangioplasty) or coronary bypass surgery. Although thrombosis can resultin death, the procedures which may have thrombosis as a side effect arethemselves are life-saving and widely used. Additionally, thrombosis mayalso result from progression of a natural disease, such asatherosclerosis. Accordingly, administration of anti-thrombotic drugs topatients who have undergone vascular procedures is often desirable.

[0101] Many anti-thrombotic drugs are known in the art. Non-limitingexamples include aspirin (acetylsalicylic acid), prostaglandin E₁,selective thromboxane A₂ inhibitors, selective thrombin inhibitors,platelet receptor GPIIb/IIIa blockers, tissue plasminogen activator,streptokinase, heparin, hirudin, bivalirudin, and kistrin and otherplatelet and/or thrombin inhibitors. As with anti-restenosis drugs,administration of anti-thrombotics locally to the site of potentialthrombosis is usually vastly preferable to systemic administration.

[0102] Additional, non-limiting examples of types of drugs that may beincorporated into depot(s) in or on stents according to the presentinvention include antineoplastic, antimitotic, antiplatelet, antifibrin,antithrombin, antibiotic, antioxidant, and antiallergic substances aswell as combinations thereof.

[0103] Depots for use in accordance with the present invention mayinclude one or more different drug(s). For example, it will often bedesirable to include two or more drugs that have additive, or evensynergistic effects. Where more than one drug is incorporated into asingle depot, it will be generally preferred to incorporate drugs thatwill not interfere with, degrade, destabilize, or otherwise interferewith one another. However, in some cases in may be desirable to includea first drug along with a second drug that reduces or alters theactivity of the first drug in a desired manner. In the same manner,different depots may include different drugs, or differentconcentrations of the same drug. The many possible permutations allowfor great flexibility in treatment.

[0104] Stents according to the present invention can be used as vehiclesfor localized delivery of drugs to cells of the walls of both the mainand branch vessels at the location of the stent. Drugs that areparticularly suitable for treatment of cells in the immediate area ofthe stent include anti-restenosis and anti-thrombotic drugs. If desired,different concentrations of drugs, or different drugs, may be includedin depot(s) located in or on different areas of the stent walls. Forexample, it may be desirable to treat the cells of the main vessel witha first drug, combination of drugs, and/or concentration of drug(s) andto treat the cells of the branch vessel with a second, different, drug,combination of drugs, and/or concentration of drug(s). As anotherexample, it may be desirable to maintain a high concentration ofanti-restenosis drug(s) near the bifurcation of the vessels. As yetanother non-limiting example, it may be desirable to maintain a highconcentration of anti-restenosis drug(s) at the three open ends (two onthe main portion and one on the branch portion) of the stent. It will beappreciated by one skilled in the art upon reading the presentdisclosure that many combinations of two or more depots are possiblewithin the spirit and scope of the present invention.

[0105] Stents according to the present invention can be used as vehiclesto deliver drug(s) to an organ, tissue, or region of the body downstreamfrom the stent. For example, stents according to the present inventionmay be positioned in an artery that supplies blood to an organ, such asthe heart, in a location close to that organ. Drug(s) that elute fromthe depot(s) in or on the stent may be carried by the blood flow to theorgan. In this way, localized delivery to tissues, organs, and bodyregions can be achieved. Using stents according to the presentinvention, a first drug, combination of drugs, and/or concentration ofdrug(s), may be delivered to an organ, tissue, or region downstream fromthe main portion of the stent while a second, different, drug,combination of drugs, and/or concentration of drug(s) is delivered to anorgan, tissue, or region downstream from the branch portion of thestent. This differential delivery can be accomplished by locating adepot having a first drug, combination of drugs, and/or concentration ofdrug(s) in or on an area of the main portion of the stent that is notcontacted by blood flowing through the branch vessel, and locating asecond depot having a second, different, drug, combination of drugs,and/or concentration of drug(s) in or on the branch portion of thestent. It will be appreciated by one skilled in the art upon reading thepresent disclosure that many combinations of two or more depots arepossible within the spirit and scope of the present invention.

[0106] Specific, and non-limiting, examples of drugs that may beincorporated into depot(s) in or on stents according to the presentinvention include the following drugs. Examples of antineoplastic and/orantimitotic drugs include docetaxel (e.g., Taxotere® from Aventis S. A.,Frankfurt, Germany) methotrexate, azathioprine, vincristine,vinblastine, fluorouracil, doxorubicin hydrochloride (e.g., Adriamycin®from Pharmacia & Upjohn, Peapack N.J.), and mitomycin (e.g., Mutamycin®from Bristol-Myers Squibb Co., Stamford, Conn.). Examples ofantiplatelet, anticoagulant, antifibrin, and antithrombin drugs includesodium heparin, low molecular weight heparins, heparinoids, hirudin,argatroban, forskolin, vapiprost, prostacyclin and prostacyclinanalogues, dextran, D-phe-pro-arg-chloromethylketone (syntheticantithrombin), dipyridamole, glycoprotein IIb/IIIa platelet membranereceptor antagonist antibody, recombinant hirudin, and thrombininhibitors such as Angiomax™ (Biogen, Inc., Cambridge, Mass.). Examplesof cytostatic or antiproliferative drugs include angiopeptin,angiotensin converting enzyme inhibitors such as captopril (e.g.,Capoten® and Capozide® from Bristol-Myers Squibb Co., Stamford, Conn.),cilazapril or lisinopril (e.g., Prinivil® and Prinzide® from Merck &Co., Inc., Whitehouse Station, N.J.); calcium channel blockers (such asnifedipine), colchicine, fibroblast growth factor (FGF) antagonists,histamine antagonists, lovastatin (an HMG-CoA reductase inhibitor, brandname Mevacor® from Merck & Co., Inc., Whitehouse Station, N.J.),monoclonal antibodies (such as those specific for Platelet-DerivedGrowth Factor (PDGF) receptors), nitroprusside, phosphodiesteraseinhibitors, prostaglandin inhibitors, suramin, serotonin blockers,steroids, thioprotease inhibitors, triazolopyrimidine (a PDGFantagonist), and nitric oxide. An example of an antiallergic agent ispermirolast potassium. Other therapeutic substances or agents that maybe used include alpha-interferon and dexamethasone. The preventative andtreatment properties of the foregoing therapeutic substances or agentsare well-known to those of ordinary skill in the art.

[0107] The present invention also provides kits comprising a stent orstents according to the present invention. In addition to a stent orstents, a kit according to the present invention may include, forexample, delivery catheter(s), balloon(s), and/or instructions for use.In kits according to the present invention, the stent(s) may be mountedin or on a balloon or catheter. Alternatively, the stent(s) may beseparate from the balloon or catheter and may be mounted therein orthereon prior to use.

[0108] While the invention has been described in conjunction withspecific embodiments and examples thereof, it is evident that manyalternatives, modifications and variations will be apparent to thoseskilled in the art upon reading the present disclosure. Accordingly, itis intended to embrace all such alternatives, modifications andvariations that fall within the spirit and broad scope of the appendedclaims.

What is claimed is:
 1. A stent for use in a bifurcated body lumen havinga main branch and a side branch, wherein the stent comprises: a radiallyexpandable generally cylindrical stent body having proximal and distalopposing ends with a body wall having a surface extending therebetween,the surface having a geometrical configuration defining a first pattern,said first pattern having first pattern struts and connectors arrangedin a predetermined configuration; and a branch portion comprised of asecond pattern, wherein said branch portion is at least partiallydetachable from said stent body.
 2. The stent of claim 1, wherein saidsecond pattern is configured according to said first pattern having atleast one absent connector.
 3. The stent of claim 2, wherein said atleast one connector is a plurality of connectors.
 4. The stent of claim1, wherein said second pattern has second pattern struts, and whereinsaid second pattern struts are more densely packed than said firstpattern struts.
 5. A stent for implantation in a bifurcated body lumenhaving a main branch and a side branch, wherein the stent comprises: atubular body having a distal end and a proximal end; and a branchportion between said distal end and said proximal end of said tubularbody, wherein in a first configuration said branch portion is flush withsaid tubular body and in a second configuration said branch portion isextended outward with respect to the tubular body.
 6. The stent of claim5, wherein said tubular body comprises a first pattern of rows of strutsand connectors, wherein said rows of struts are connected to each otherby said connectors.
 7. The stent of claim 6, wherein said branch portioncomprises a second pattern of rows of struts and connectors, whereinsaid second pattern of rows of struts and connectors has a differentconfiguration than said first pattern of rows of struts and connectors.8. The stent of claim 7, wherein said different configuration includesdifferent strut lengths.
 9. The stent of claim 7, wherein said differentconfiguration includes at least one row having a different strutdensity.
 10. A stent for placement at a vessel bifurcation, wherein thestent comprises: an alternating series of rows of struts connected byrows of connectors configured in a tubular structure; and a branchaccess opening in the tubular structure, said branch access openingcharacterized by one of said rows of connectors having at least oneabsent connector.
 11. The stent of claim 10, wherein said at least oneabsent connector comprises a plurality of absent connectors.
 12. Thestent of claim 10, further comprising a branch portion adjacent to saidbranch access opening.
 13. The stent of claim 12, wherein said branchportion comprises a geometrical configuration which is configured toexpand independently of said tubular structure.
 14. A stent system forplacement in a bifurcated body lumen, the system comprising: a catheterfor insertion into said body lumen; a balloon positioned on saidcatheter; and a stent positioned on said balloon, said stent comprisinga body wall having proximal and distal opposing ends with a surfaceextending therebetween, the surface having a geometrical configurationdefining a first pattern, said first pattern having first pattern strutsand connectors arranged in a predetermined configuration, and a branchportion having a geometrical configuration defining a second pattern,wherein said branch portion is at least partially detached from saidsurface.
 15. The system of claim 14, wherein said balloon has aprotruding portion in the vicinity of said branch portion for expandingsaid branch portion into a branch vessel.
 16. The system of claim 14,further comprising a side sheath positioned alongside said catheter,wherein said side sheath is positioned through said branch portion,thereby detaching it from said surface.
 17. The system of claim 16,wherein said side sheath further comprises a second balloon forexpansion of said branch portion.
 18. A method of stenting a vesselbifurcation, the method comprising: providing a stent system forplacement in a bifurcated body lumen, wherein the system includes acatheter for insertion into the vessel, a balloon positioned on saidcatheter, and a stent positioned on said balloon, said stent comprisinga body wall having a surface extending therebetween, the surface beingcomprised of a first pattern, said first pattern having first patternstruts and connectors arranged in a particular configuration, and abranch portion comprised of a second pattern, wherein said branchportion is at least partially detached from said surface; advancing saidstent system into a main vessel until the stent system is just proximalto the bifurcation; expanding said balloon so as to expand said stentbody wall; and expanding said branch portion so that said branch portionextends into the branch vessel.
 19. A bifurcation stent, comprising: atubular member having an inner diameter and an outer diameter defining awall therebetween, the wall having a geometrical configuration defininga pattern; and an expandable branch structure formed in the wall of thetubular structure and interrupting the wall pattern, the expandablebranch structure having a first ring connected to the tubular member anda second ring connected to the first ring, the first ring beingconcentric with the second ring, wherein the first ring and the secondring are movable from an unexpanded configuration to an expandedconfiguration, in the unexpanded configuration the first and secondrings are disposed along the wall and in the expanded configuration thefirst and second rings extend outwardly from the tubular member.
 20. Thestent according to claim 19, wherein the tubular member has alongitudinal axis and the expandable branch structure is disposedsubstantially perpendicular to the longitudinal axis in the expandedconfiguration.
 21. The stent according to claim 1, wherein the tubularmember comprises a plurality of undulating rings disposed along thelongitudinal axis and the undulating rings are connected by connectors.22. The stent according to claim 21, wherein the first and second ringshave a common axis disposed substantially perpendicular to thelongitudinal axis in the unexpanded configuration.
 23. The stentaccording to claim 19, wherein the branch structure includes a supportring.
 24. The stent according to claim 23, wherein the support ring is acontinuous loop.
 25. The stent according to claim 23, wherein thesupport ring comprises a discontinuous portion.
 26. A stent forimplantation into the body comprising: a tubular structure with a distaland proximal end with tubular walls of coiled struts capable ofexpansion in a manner increasing said tubular structure's diameter whenwithin the body and which can form rings if completely expanded;periodic connections between the individual coiled struts that arecapable of expansion in a direction orthogonal to the diameter of thetubular body; and containing a branch portion that is contiguous withthe tubular body of said stent when in an unexpanded form but whichexpands at an angle to the length dimension of the tubular body when inan expanded configuration.
 27. The stent of claim 26 where said branchportion is created by removing one or more of the periodic connectionsbetween the coiled struts.
 28. The stent of claim 26 where said branchportion is created by adding a geometric structure of coiled struts thatforms one or more circles when expanded.
 29. The stent of claim 26 wheresaid branch portion is created by adding a geometric structure of coiledstruts that forms one or more ovals when expanded.